Switch to Apache HC5 HttpClient. (#4126)

docs/src/main/asciidoc/_configprops.adoc

@@ -2,7 +2,7 @@
 |Name | Default | Description
 
 |eureka.client.eureka-connection-idle-timeout-seconds | `+++30+++` | Indicates how much time (in seconds) that the HTTP connections to eureka server can stay idle before it can be closed. In the AWS environment, it is recommended that the values is 30 seconds or less, since the firewall cleans up the connection information after a few mins leaving the connection hanging in limbo.
-|eureka.client.eureka-server-connect-timeout-seconds | `+++5+++` | Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by org.apache.http.client.HttpClient and this setting affects the actual connection creation and also the wait time to get the connection from the pool.
+|eureka.client.eureka-server-connect-timeout-seconds | `+++5+++` | Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by {@link HttpClient} and this setting affects the actual connection creation and also the wait time to get the connection from the pool.
 |eureka.client.eureka-server-d-n-s-name |  | Gets the DNS name to be queried to get the list of eureka servers.This information is not required if the contract returns the service urls by implementing serviceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.
 |eureka.client.eureka-server-port |  | Gets the port to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS.This information is not required if the contract returns the service urls eurekaServerServiceUrls(String). The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime.
 |eureka.client.eureka-server-read-timeout-seconds | `+++8+++` | Indicates how long to wait (in seconds) before a read from eureka server needs to timeout.

spring-cloud-netflix-eureka-client/pom.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+		 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 		 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<parent>
@@ -14,7 +15,7 @@
 	<description>Spring Cloud Netflix Eureka Client</description>
 	<properties>
 		<!-- Why do I need this now? -->
-		<maven.javadoc.failOnError>false</maven.javadoc.failOnError>		
+		<maven.javadoc.failOnError>false</maven.javadoc.failOnError>
 	</properties>
 	<dependencies>
 		<dependency>
@@ -67,6 +68,10 @@
 			<artifactId>spring-boot-autoconfigure-processor</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.apache.httpcomponents.client5</groupId>
+			<artifactId>httpclient5</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-security</artifactId>

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/EurekaClientConfigBean.java

@@ -25,6 +25,7 @@ import java.util.Objects;
 import com.netflix.appinfo.EurekaAccept;
 import com.netflix.discovery.EurekaClientConfig;
 import com.netflix.discovery.shared.transport.EurekaTransportConfig;
+import org.apache.hc.client5.http.classic.HttpClient;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.context.properties.ConfigurationProperties;
@@ -126,14 +127,14 @@ public class EurekaClientConfigBean implements EurekaClientConfig, Ordered {
 	/**
 	 * Indicates how long to wait (in seconds) before a connection to eureka server needs
 	 * to timeout. Note that the connections in the client are pooled by
-	 * org.apache.http.client.HttpClient and this setting affects the actual connection
-	 * creation and also the wait time to get the connection from the pool.
+	 * {@link HttpClient} and this setting affects the actual connection creation and also
+	 * the wait time to get the connection from the pool.
 	 */
 	private int eurekaServerConnectTimeoutSeconds = 5;
 
 	/**
 	 * Gets the name of the implementation which implements BackupRegistry to fetch the
-	 * registry information as a fall back option for only the first time when the eureka
+	 * registry information as a fallback option for only the first time when the eureka
 	 * client starts.
 	 *
 	 * This may be needed for applications which needs additional resiliency for registry

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/http/DefaultEurekaClientHttpRequestFactorySupplier.java

@@ -19,9 +19,12 @@ package org.springframework.cloud.netflix.eureka.http;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
-import org.apache.http.impl.client.CloseableHttpClient;
-import org.apache.http.impl.client.HttpClientBuilder;
-import org.apache.http.impl.client.HttpClients;
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
+import org.apache.hc.client5.http.impl.classic.HttpClients;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
+import org.apache.hc.client5.http.io.HttpClientConnectionManager;
+import org.apache.hc.client5.http.ssl.SSLConnectionSocketFactoryBuilder;
 
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
@@ -32,18 +35,16 @@ import org.springframework.lang.Nullable;
  * {@link HttpClients}.
  *
  * @author Marcin Grzejszczak
+ * @author Olga Maciaszek-Sharma
  * @since 3.0.0
  */
 public class DefaultEurekaClientHttpRequestFactorySupplier implements EurekaClientHttpRequestFactorySupplier {
 
 	@Override
 	public ClientHttpRequestFactory get(SSLContext sslContext, @Nullable HostnameVerifier hostnameVerifier) {
-		HttpClientBuilder httpClientBuilder = HttpClients.custom();
-		if (sslContext != null) {
-			httpClientBuilder = httpClientBuilder.setSSLContext(sslContext);
-		}
-		if (hostnameVerifier != null) {
-			httpClientBuilder = httpClientBuilder.setSSLHostnameVerifier(hostnameVerifier);
+		HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
+		if (sslContext != null || hostnameVerifier != null) {
+			httpClientBuilder.setConnectionManager(buildConnectionManager(sslContext, hostnameVerifier));
 		}
 		CloseableHttpClient httpClient = httpClientBuilder.build();
 		HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
@@ -51,4 +52,18 @@ public class DefaultEurekaClientHttpRequestFactorySupplier implements EurekaClie
 		return requestFactory;
 	}
 
+	private HttpClientConnectionManager buildConnectionManager(SSLContext sslContext,
+			HostnameVerifier hostnameVerifier) {
+		SSLConnectionSocketFactoryBuilder sslConnectionSocketFactoryBuilder = SSLConnectionSocketFactoryBuilder
+				.create();
+		if (sslContext != null) {
+			sslConnectionSocketFactoryBuilder.setSslContext(sslContext);
+		}
+		if (hostnameVerifier != null) {
+			sslConnectionSocketFactoryBuilder.setHostnameVerifier(hostnameVerifier);
+		}
+		return PoolingHttpClientConnectionManagerBuilder.create()
+				.setSSLSocketFactory(sslConnectionSocketFactoryBuilder.build()).build();
+	}
+
 }